使用日志记录模块重命名 python 中的日志文件

Question

I need to rename a logging file but continue logging to it afterwards. I'm running Python 3.x and using a logging module to create logs.

logger = logging.getLogger(r'mylogger')
handler = logging.FileHandler(r'mylog.txt', mode = r'w')
logger.addHandler(handler)
logger.info(r'msg 1')
logger.info(r'msg 2')

handler.renameFile(r'my_newlog.txt')  # <--- Is something like this possible?

logger.info(r'msg 3')

Does anyone know if something like this is possible? If no, how would I go about doing it? One idea that I had was to close the file ( handler.close() ), remove the handler from the logger, rename the old file, create a new handler with the new file name and add it to the logger. The issue however is that I would need to create a completely identical handler, ie it would need to have the same attributes as the old one (with exception of the file name of course). Is there a simple way to store old attributes and then use them to set the attributes of the new handler?

Any help is appreciated.

Answer 1

Late the party, but I ran into this problem as well and here's how I've (tentatively) solved it. Needs more testing though.

Note in my case, I do have access to the previous handler, so I just wound up using the same handler configuration I used earlier. I agree a FileHandler.'rename_file()' method would be great. One could likely be cooked up by sub-classing FileHandler(), but that's an exercise for another day.

#!/usr/bin/env python3

import os
import logging

logger_name1 = 'my_log.txt'
logger_name2 = 'my_new_log.txt'

logger = logging.getLogger('mylogger')
logger.level = logging.INFO
handler = logging.FileHandler(logger_name1, mode='w')
logger.addHandler(handler)
logger.info('msg 1')
logger.info('msg 2')

# handler.renameFile('my_newlog.txt')  # <--- Is something like this possible?

logger.removeHandler(handler)

# Rename the logfile on disk
os.rename(logger_name1, logger_name2)

# New handler using new filename.  Note the 'append' flag
new_handler = logging.FileHandler(logger_name2, mode='a')
logger.addHandler(new_handler)

# Try out the new logfile
logger.info('msg 3')

Answer 2

I had the same problem and was successful with little adaption of the solution suggested by JS

#!/usr/bin/env python3

import os
import logging
import shutil

logger_name1 = 'my_log.txt'
logger_name2 = 'my_new_log.txt'

logger = logging.getLogger('mylogger')
logger.level = logging.INFO
handler = logging.FileHandler(logger_name1, mode='w')
logger.addHandler(handler)
logger.info('msg 1')
logger.info('msg 2')

# handler.renameFile('my_newlog.txt')  # <--- Is something like this possible?
handler.close()     # need to close to release file handle
logger.removeHandler(handler)

# Rename the logfile on disk
#os.rename(logger_name1, logger_name2) # error if destination already exists
shutil.move(logger_name1, logger_name2)

# New handler using new filename.  Note the 'append' flag
new_handler = logging.FileHandler(logger_name2, mode='a')
logger.addHandler(new_handler)

# Try out the new logfile
logger.info('msg 3')

Answer 3

import glob
import logging
import logging.handlers

LOG_FILENAME = 'logging_rotatingfile_example.out'

# Set up a specific logger with our desired output level
my_logger = logging.getLogger('MyLogger')
my_logger.setLevel(logging.DEBUG)

# Add the log message handler to the logger
handler = logging.handlers.RotatingFileHandler(
              LOG_FILENAME, maxBytes=20, backupCount=5)

my_logger.addHandler(handler)

# Log some messages
for i in range(20):
    my_logger.debug('i = %d' % i)

# See what files are created
logfiles = glob.glob('%s*' % LOG_FILENAME)

for filename in logfiles:
    print(filename)

The result should be 6 separate files, each with part of the log history for the application:

logging_rotatingfile_example.out
logging_rotatingfile_example.out.1
logging_rotatingfile_example.out.2
logging_rotatingfile_example.out.3
logging_rotatingfile_example.out.4
logging_rotatingfile_example.out.5